Novel sophorose lipids from microbial conversion of 2-alkanols

Abstract

Using glucose/rac. 2-alkanols as carbon sources for the cultivation of Candida bombicola novel types of sophorose lipids were isolated as major products.Among all lipophilic constituents 2-alkanol was found as the major hydrophobic moiety (> 75%) involved in three new sophorose lipids differing only in the degree of acetylation of the sophorose. Additional monooxygenation of the alcohol leads to the incorporation of 2,(e-1)-alkandiol; glycolipids with up to four glucose units were obtained.

Production of new‐to‐nature sophorolipids by cultivating the yeast Candida bombicola on unconventional hydrophobic substrates

“…Brakemeier et al (1995Brakemeier et al ( , 1998a used secondary alcohols (C12-C16) as the lipophilic carbon source and observed direct incorporation for the majority of the substrate. Primary alcohols can be applied as well, but these tend to be largely metabolized in b-oxidation unless an adjusted medium with high glucose and yeast extract content is provided.…”

“…Despite these variations, the sophorolipid fatty acid tail is limited to 16 or 18 carbon atoms. This restricted length hampers the use of sophorolipids in certain cleaning purposes; molecules with a shorter fatty acid tail would broaden up the application range as this will cause a shift in the hydrophilic/hydrophobic balance of the molecule, resulting in better water solubility and in some cases improved surface lowering capacities (Brakemeier et al, 1995). Yet, these molecules are not readily obtained by a simple low cost fermentation process.…”

Structure Elucidation and Characterization of Microbial 2-Tridecyl Sophorosides (Biosurfactants)

“…These alkyl sophorosides showed a better surface activity than the classical sophorolipids and lowered the surface tension of water from 72 mN m -1 to 31 mN m -1 . Furthermore, Brakemeier et al (1995Brakemeier et al ( , 1998b showed that other secondary alcohols, such as 2-tetradecanol or 2-hexadecanol and ketones with an even number of carbon atoms like 2-, 3-, and 4-dodecanone, can be converted to the corresponding alkyl sophorosides by C. bombicola.…”

“…the co-substrate 2-dodecanone. By the use of 2-tetradecanol or 2-hexadecanol as co-substrate they obtained around 24 g l -1 alkyl sophorosides after 9 days of cultivation (Brakemeier et al, 1995). Since the 2-tridecanone cultivation was a preliminary experiment, there is potential for improvement, e.g.…”

“…Glucosyltransferase 3 + acetylation To compare the values of our 2-tridecyl sophorosides with those of the corresponding 2-dodecyl sophorosides (one carbon atom less) and 2-tetradecyl sophorosides (one carbon atom more), those compounds (Brakemeier, 1997;Brakemeier et al, 1998a) were tested as well in the surface tension measurements. According to their lower lipophilic character (SL-E 2 -12 , 12 carbon atoms) or, on the other hand, stronger lipophilic character (SL-E 2 -14 , 14 carbon atoms) these very similar glycolipids effected somewhat lower values (31 mN m .…”